Metallic coating and process of producing the same



Feb. 10, 1931. c. G. FINK ET AL 1,792,082

METALLIC COATING AND PROCESS OF PRODUCING THE SAME Filed Jan. 13, 1926NicKel T-o undaiwbn me kol 071 7'0 mium (Jo-w?! 1%.... ww

Patented Feb. 10, 1931 UNITED STATES PATENT OFFICE COLIN G. FINK AND LICHI PAN, OF NEW YORK, N. Y., ASSIGNORS TO CHEMICAL TREATMENT COMPANY,INC., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK METALLIC COATING ANDPROCESS OF PRODUCING THE SAME Application filed January 13, 1926. SerialNo. 81,099.

This invention relates to metallic coatings which are protective,resistant, decorative, refleeting, and to processes of producing thesame, and aims to provide improvements therein. M

Fink (one of the present applicants) and associates, have heretoforeproduced resistant and protective coatings composed in whole or in partof chromium, and have devised several kinds of such coatings and severalprocesses of producing the same. Decorative (including reflecting)coatings and processes of producing the same have also been devised. Thepresent invention is the result of the continuation of theirinvestigations in this direction, having for object to obtain aprotective and resistant coating, a decorative coating, and a decorativeand protective coating combining excellent qualities with an economicaland readily performed procedure for obtaining such coatings. The presentinvention accordingly provides a coating having excellent protective andresistant properties (that is, resistance to corrosion, acids, wear),and/or excellent decorative and reflecting properties, and improvedprocesses of producing such coatings carried out in readily performedoperations and resulting in an economical production of such coatings.

The annexed drawing shows a form of embodiment of an article (sheet ofmetal) having thereon the decorative, protective and resistant coating,the drawing being explanatory and the thickness of the plates beingexaggerated.

Accordin to the present invention, a foundation meta as for exampleiron, steel, etc, designated by the letter F on the accompanyingdrawing, is coated with nickel in any suitable manner, preferably byelectrode osition, and if, as is usually the case, the nic el plate isbrittle and not firmly adherent, the coating or plate is treated insuitable manner, as by heating, to make the nickel ductile and adherent.

The heating of the nickel-plated article is referably carried out in aneutral or reducmg atmosphere, so as to minimize the oxidation, and theheating is preferably carried to a red heat, in order to bring about anadhesion or alloying between the nickel plate and the foundation metal,and also to produce a healing of defects (usually designated pin holes)in the said plate.

The nickel plate N may be made of any desired thickness, but a thicknessof about mill (.0005 inch) is ordinarily used.

If the nickel plate is of the quality which is adherent and withoutdefects, heating might be omitted, but it is generally advisable to heattreat the nickel plate, as indicated above.

After the foundation metal F has been provided with the ductile andadherent coat or plate N of nickel, a plate C of chromium is plated onthe nickel. Ordinarily, the chromium plate is .0003 to .0005 inch thick.

Oxidation of the nickel surface, which may be produced by heating orotherwise, is re moved prior to the deposit of the chromium. Thisde-oxidation is conveniently carried out in the chromium electroplatingbath itself. Release or evolution of hydrogen is arranged to take placeat thecathode, and when using chromic acid solutions such an evolutionof hydrogen is made to take place therein. This evolution of hydrogen inelectrolyzing with the chromic acid solutions is found to satisfactorilyde-oxidize the nickel surface, and to result in the deposit of anadherent coat of chromium on the nickel, the quality of which chromiumplate may be determined by the conditions of the plating. A brlght orlustrous chromium plate may be producedby following the process setforth in the Flnk application filed September 19, 1925, Serial No.57,290.

By depositing such a brlght chromium plate, bright metal surfaces whichare protected from and resistant to var ous COIIOSlVG conditions andagents, and acids, and very resistant to wear, are obtained Withoutunusual manufacturing expedients, such as grinding, polishing, etc.There 1s no necessar preparation of the article between the nic elplating bath, and the chromlum plating bath, except the usual andreadily performed operation of heat treatment.

It has been found. that these reslstant coats of nickel and chromiumgive very nearly the same resistance to corrosive agents, acids, etc. aschromium coats from which the pinhole defects have been eliminated.

The invention has the advantage that the nickel adheres more readily toand alloys more readily with ferro metals than chr0- mium, that is, whenthe nickel has been produced or treated in a manner to eliminate thebrittleness of ordinary electrodeposits of nickel plate. It has thefurther advantage that nickel oxidizes less extensively and readily athigher temperatures than chromium, and the further advantage that theoxide of nickel may be removed by hydrogen in electrolytic baths,whereas chromium oxide is not so affected.

Cobalt may be substituted for nickel and is included in the scope of theclaims as the equivalent of nickel. I

By preparing the nickel plate, as by polishing, before depositing thechromium and by electrodepositing the chromium according to conditionsof current density, temperature, etc., set forth in the application ofColin G. Fink, Serial No. 57,290, filed September 19th, 1925, amirror-like, image reflecting surface may be obtained. By heat-treatingthe nickel plate, polishing and depositing thereon a chromium plate ofthe quality which is image-reflecting when deposited on a polishedsurface, mirrors and reflectors having a high reflecting value andespecially suitable for outdoor use, are obtained. As a decorativesurface, the resemblance of the present coatings is close to silver.

The process may be carried out by other modes of procedure than thatherein specifically described, and the coatings may have other forms ofembodiments than that specifically illustrated and described.

What is claimed is:

1. An article having a protective and resistant coating thereon, saidcoating comprising a heat-treated plate of nickel on the foundationmetal of the article, and a plate of chromium on said plate of nickel.

2. An article having a. protective and resistant coating thereon, said.coating being bright, comprising a heat-treated plate of nickel on thefoundation-metal of the article, and a plate of chromium on said plateof nickel.

3. A method of producing protective and resistant coatings on metalarticles, comprising electrodepositing nickel on said article,heat-treating said nickel coat, removing oxidation of said nickel whichmay have resulted from heat treatment, and electrodepositing a plate ofchromium on said nickel plate.

4. A method of producing protective and resistant coatings on metalarticles, comprising electrodepositing nickel on said articles.heat-treating said nickel coat, and electrodepositing chromium on saidnickel plate with signed our names.

COLIN G. FINK. LI CHI PAN.

